Turbine Airfoil Cooling System with Pin Fin Cooling Chambers

ABSTRACT

A cooling system for a turbine airfoil having at least one pin fin with a dimpled outer surface is disclosed. The dimpled outer surface increases the cooling efficiency of the pin fin, which creates numerous efficiencies, including thermal efficiencies, manufacturing efficiencies and the like. The dimples may be formed from shapes including, but not limited to, circular, oval, racetrack, and hemispherical. The dimples may be aligned in a variety of configurations.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Development of this invention was supported in part by the United States Department of Energy, Contract No. DE-FC26-05NT42644, H2 Advanced Hydrogen Turbine Development, Phase 2. Accordingly, the United States Government may have certain rights in this invention.

FIELD OF THE INVENTION

This invention is directed generally to turbine airfoils, and more particularly to cooling systems in hollow turbine airfoils.

BACKGROUND

Typically, gas turbine engines include a compressor for compressing air, a combustor for mixing the compressed air with fuel and igniting the mixture, and a turbine blade assembly for producing power. Combustors often operate at high temperatures that may exceed 2,500 degrees Fahrenheit. Typical turbine combustor configurations expose turbine blade assemblies to these high temperatures. As a result, turbine blades must be made of materials capable of withstanding such high temperatures. In addition, turbine blades often contain cooling systems for prolonging the life of the blades and reducing the likelihood of failure as a result of excessive temperatures.

Typically, turbine blades are formed from a root portion having a platform at one end and an elongated portion forming a blade that extends outwardly from the platform coupled to the root portion. The blade is ordinarily composed of a tip opposite the root section, a leading edge, and a trailing edge. The inner aspects of most turbine blades typically contain an intricate maze of cooling channels forming a cooling system. The cooling channels in a blade receive air from the compressor of the turbine engine and pass the air through the blade. The cooling channels often include multiple flow paths that are designed to maintain all aspects of the turbine blade at a relatively uniform temperature. However, centrifugal forces and air flow at boundary layers often prevent some areas of the turbine blade from being adequately cooled, which results in the formation of localized hot spots. Localized hot spots, depending on their location, can reduce the useful life of a turbine blade and can damage a turbine blade to an extent necessitating replacement of the blade. Thus, a need exists for a cooling system capable of providing sufficient cooling to turbine airfoils.

SUMMARY OF THE INVENTION

This invention relates to improvements in a turbine airfoil cooling system for a turbine airfoil used in turbine engines. In particular, the turbine airfoil cooling system includes a plurality of internal cavities positioned between outer walls of the turbine airfoil. The cooling system may include one or more pin fins having one or more dimples on outer surfaces of the pin fins. The dimpled pin fins may more efficiently remove heat from the turbine airfoil than conventional cooling systems.

The turbine airfoil may be formed from any appropriate configuration. In at least one embodiment, the turbine airfoil may be formed from a generally elongated, hollow airfoil having a leading edge, a trailing edge, a tip section at a first end, a root coupled to the airfoil at an end generally opposite the first end for supporting the airfoil and for coupling the airfoil to a disc, and a cooling system formed from at least one cavity in the elongated, hollow airfoil. The turbine airfoil may be formed from an outer wall forming the generally elongated airfoil.

The cooling system may include a pin fin having an outer surface with one or more dimples that are generally concave. The dimple may have a generally circular shape at an intersection with the outer surface of the at least one dimple, a generally oval shape at an intersection with the outer surface of the at least one dimple, a generally racetrack shape with two curved ends and two generally linear sides at an intersection with the outer surface of the at least one dimple, a generally hemispherical shape, or other appropriate shape.

The pin fin may have any appropriate configuration. In at least one embodiment, the pin fin may be generally cylindrical. The outer surface of the pin fin may include a plurality of dimples. The dimples may be aligned into horizontal rows that are offset from dimples in adjacent rows. The dimples may be positioned such that the dimples extend into the pin fin between about ½ percent to about 20 percent of the width of the pin fin.

An advantage of this invention is that the dimpled pin fins offer reduced pressure losses, increase surface area for convective heat transfer and greater design flexibility.

Another advantage of this invention is that the dimpled pin fins may enable a reduction in the amount of cooling fluids sent through the turbine airfoil cooling system without compromising the cooling capabilities of the turbine airfoil cooling system, thereby increasing the efficiency of the turbine engine.

These and other embodiments are described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the presently disclosed invention and, together with the description, disclose the principles of the invention.

FIG. 1 is a perspective view of a turbine airfoil having features according to the instant invention.

FIG. 2 is a cross-sectional view of the turbine airfoil shown in FIG. 1 taken along line 2-2.

FIG. 3 is a perspective view of a pin fin that is a component of the turbine airfoil cooling system.

FIG. 4 is a perspective view of an alternative configuration of a dimple.

FIG. 5 is a perspective view of another alternative configuration of a dimple.

FIG. 6 is a perspective view of yet another alternative configuration of a dimple.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1-6, this invention is directed to improvements in a turbine airfoil cooling system 10 for a turbine airfoil 12 used in turbine engines. In particular, the turbine airfoil cooling system 10 includes a plurality of internal cavities 14, as shown in FIG. 2, positioned between outer walls 16 of the turbine airfoil 12. The cooling system 10 may include one or more pin fins 18 having one or more dimples 20 on outer surfaces 22 of the pin fins 18. The dimpled pin fins 18 may more efficiently remove heat from the turbine airfoil 12 than conventional cooling systems 10.

The turbine airfoil 12 may be a stationary turbine vane, a rotatable turbine blade or other appropriate structure. In the embodiment shown in FIGS. 1 and 2, the turbine airfoil 12 is a turbine blade. The turbine airfoil 12 may be formed from a generally elongated, hollow airfoil 28 coupled to a root 30 at a platform 32. The turbine airfoil 12 may be formed from conventional metals or other acceptable materials. The generally elongated airfoil 28 may extend from the root 30 to a tip section 34 and include a leading edge 36 and trailing edge 38. Airfoil 28 may have an outer wall 16 adapted for use, for example, in a first stage of an axial flow turbine engine. Outer wall 16 may form a generally concave shaped portion forming the pressure side 24 and may form a generally convex shaped portion forming the suction side 26. The cavity 14, as shown in FIG. 2, may be positioned in inner aspects of the airfoil 28 for directing one or more gases, which may include air received from a compressor (not shown), through the airfoil 28 to reduce the temperature of the airfoil 28. The cavity 14, and thus the turbine airfoil cooling system 10, may be arranged in various configurations and is not limited to a particular flow path.

The turbine airfoil cooling system 10 may include one or more pins fins 18 positioned in the cooling system 10. Pin fin 18 may extend through a cooling fluid flow channel generally nonparallel to the flow of cooling fluids through the cooling fluid flow channel. In one embodiment, the pin fin 18 may be positioned generally. orthogonal to the flow of cooling fluids through the cooling fluid flow channel. The pin fins 18 may have any appropriate size. The pin fins 18 may impede flow of the cooling fluids and increase the convective cooling of the airfoil 12. The pin fins 18 may be positioned in any appropriate position, alignment and configuration to enhance the cooling capabilities of the turbine airfoil cooling system 10. The pin fins 18 may have any appropriate size and may be formed from any appropriate material. The pin fins 18 may extend from the an outer wall 16 at the pressure side 24 to the outer wall 16 forming the suction side 26. In other embodiments, the pin fins 18 may extend between other aspects of the turbine airfoil cooling system 10. The pin fins 18 may be generally cylindrical or have other appropriate configurations. In particular, the pin fins 18 may have cross-sectional shapes such as, but not limited to, cylindrical, elliptical or oval.

As shown in FIG. 3, the pin fins 18 may include one or more dimples 20. The dimples 20 may enhance the thermal capabilities of the pin fins 18. In particular, the dimples 20 may reduce drag, reduce pressure loss, and increase the surface area of the pin fins 18. The dimples 20 may have any appropriate configuration and may be generally concave in configuration. In particular, the dimples 20 may have an oval shape at an intersection with the outer surface 22, as shown in FIG. 3, a circular shape at an intersection with the outer surface 22, as shown in FIG. 4, a racetrack shape at an intersection with the outer surface 22, as shown in FIG. 5, a hemispherical shape at an intersection with the outer surface 22, as shown in FIG. 6, or another appropriate shape. The generally racetrack shape shown in FIG. 5 includes two curved ends 40 and two generally linear sides 42 at an intersection with the outer surface 22 of the dimple 20.

The dimples 20 may be positioned on a pin fin 18 such that the dimples 20 are positioned randomly about the outer surface 22 of the pin fin. Alternatively, the dimples 20 may be aligned into horizontal rows 44 that are offset from dimples 20 in adjacent rows 44, as shown in FIG. 3. The dimples 20 may be positioned in any pattern that increases the thermal efficiency and reduces the drag of the pin fin 18. In at least one embodiment, one or more dimples 20 may be positioned such that the dimple 20 extends into the pin fin 18 between about ½ percent to about 20 percent of the width of the pin fin 18. In one embodiment, the dimples 20 may be positioned such that the dimples 20 cover between about 20 percent and about 100 percent of the outer surface area of a pin fin 18. The pin fins 18 may be manufactured with a blade core manufacturing process referred to as Tomo Lithography Molding, by Mikro Systems, Inc.

During operation, cooling fluids are passed through the turbine airfoil cooling system 10 to cool the turbine airfoil 12 during turbine engine operation. A portion of the cooling fluids may encounter the pin fins 18 positioned in the cooling system 10 and contact the pins fins 18 and the dimples 20 thereon. The dimples 20 increase the surface area of the outer surface 22 of the pin fins 22 and thereby increase the cooling efficiency of the pin fins 22 and the turbine airfoil cooling system 10. The dimples 20 may also reduce the amount of pressure loss associated with conventional pin fins 18.

The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of this invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of this invention. 

1. A turbine airfoil, comprising: a generally elongated, hollow airfoil having a leading edge, a trailing edge, a tip section at a first end, a root coupled to the airfoil at an end generally opposite the first end for supporting the airfoil and for coupling the airfoil to a disc, and a cooling system formed from at least one cavity in the elongated, hollow airfoil; an outer wall forming the generally elongated airfoil; wherein the cooling system includes at least one pin fin having an outer surface with at least one dimple.
 2. The turbine airfoil of claim 1, wherein the at least one dimple has a generally circular shape at an intersection with the outer surface of the at least one dimple.
 3. The turbine airfoil of claim 1, wherein the at least one dimple has a generally oval shape at an intersection with the outer surface of the at least one dimple.
 4. The turbine airfoil of claim 1, wherein the at least one dimple has a generally racetrack shape with two curved ends and two generally linear sides at an intersection with the outer surface of the at least one dimple.
 5. The turbine airfoil of claim 1, wherein the at least one dimple has a generally hemispherical shape.
 6. The turbine airfoil of claim 1, wherein the outer surface of the pin fin includes a plurality of dimples.
 7. The turbine airfoil of claim 6, wherein the dimples are aligned into horizontal rows that are offset from dimples in adjacent rows.
 8. The turbine airfoil of claim 1, wherein the at least one dimple extends into the pin fin between about ½ percent to about 20 percent of the width of the pin fin.
 9. The turbine airfoil of claim 1, wherein the outer surface of the at least one pin fin includes dimples covering between about 20 percent and about 100 percent of the outer surface of the at least one pin fin.
 10. A turbine airfoil, comprising: a generally elongated, hollow airfoil having a leading edge, a trailing edge, a tip section at a first end, a root coupled to the airfoil at an end generally opposite the first end for supporting the airfoil and for coupling the airfoil to a disc, and a cooling system formed from at least one cavity in the elongated, hollow airfoil; an outer wall forming the generally elongated airfoil; wherein the cooling system includes a plurality of pin fins having an outer surface with a plurality of dimples.
 11. The turbine airfoil of claim 10, wherein at least one of the plurality of dimples has a generally circular shape at an intersection with the outer surface of the dimple.
 12. The turbine airfoil of claim 10, wherein at least one of the plurality of dimples has a generally oval shape at an intersection with the outer surface of the dimple.
 13. The turbine airfoil of claim 10, wherein at least one of the plurality of dimples has a generally racetrack shape with two curved ends and two generally linear sides at an intersection with the outer surface of the dimple.
 14. The turbine airfoil of claim 10, wherein at least one of the plurality of dimples has a generally hemispherical shape.
 15. The turbine airfoil of claim 10, wherein the dimples are aligned into horizontal rows that are offset from dimples in adjacent rows.
 16. The turbine airfoil of claim 10, wherein the at least one dimple extends into the pin fin between about ½ percent to about 20 percent of the width of the pin fin.
 17. The turbine airfoil of claim 10, wherein the outer surface of the at least one pin fin includes dimples covering between about 20 percent and about 100 percent of the outer surface of the at least one pin fin.
 18. A turbine airfoil, comprising: a generally elongated, hollow airfoil having a leading edge, a trailing edge, a tip section at a first end, a root coupled to the airfoil at an end generally opposite the first end for supporting the airfoil and for coupling the airfoil to a disc, and a cooling system formed from at least one cavity in the elongated, hollow airfoil; an outer wall forming the generally elongated airfoil; wherein the cooling system includes a plurality of generally cylindrical pin fins having an outer surface with a plurality of concave dimples that are aligned into horizontal rows that are offset from dimples in adjacent rows.
 19. The turbine airfoil of claim 18, wherein at least one of the plurality of dimples has a generally oval shape at an intersection with the outer surface of the dimple.
 20. The turbine airfoil of claim 18, wherein at least one of the plurality of dimples has a generally racetrack shape with two curved ends and two generally linear sides at an intersection with the outer surface of the dimple. 